PURPOSE: To make the display of characters and the like possible on the inner surface of a mold easily at a low cost in a short period time by a method wherein a lettering member is fixed onto the surface of the mold.

CONSTITUTION: A linear lettering member 4 displaying characters, figures, symbols and the like (hereinafter referred to as characters and the like) abuts against the inner surface 3, which corresponds to the side wall of a mold 1, of the mold 1. At the same time, a proper member of threaded holes are bored on the rear face of the lettering member 4 so as to be screwed by bolts 7... inserted through holes 6... for bolt, each of which is piercingly machined from the outer surface 5 of the mold, in order to fix the lettering member to the inner surface of the mold. Or the lettering member 4 is fitted to a groove 10, which is formed by NC machining, electrical discharge machining or the like so as to correspond to the lettering member 4, and threadingly attached by the bolts 7 from the outer surface of the mold in order to be fixed. Thus, projected lettering part for forming recessed character or the like can be formed easily on the inner surface 3 of the mold at a low cost in a short period of time.